Conventional techniques of manufacturing carbon and glass fiber reinforced articles have used labor intensive wet layup or prepreg techniques using layers of woven cloth or matt. In attempts to speed up the process the reinforcing fibers have been chopped up and mixed with one of the components of a catalyst-cured resin system thereby allowing the fibers to be injected into a molding die. The latter process while being quick and easy to handle suffers a fundamental drawback. The random orientation of the reinforcing fibers produces a cast structure of uniform strength in all directions but which is of inadequate strength in areas of high stress. While the layup and prepreg techniques can be used to provide the necessary strength, results may vary and these are inefficient and unsuitable for economic production.
Reinforcement preforms can be knitted in the same way as socks and gloves. The basic preform is then folded and tacked or stitched together before being loaded into a die to be impregnated with injected resin. This arrangement still provides a component in which the reinforcement lacks sufficient strength in regions of lateral stress, such as at a junction between two orthogonal sections. This invention seeks to overcome this drawback.